1. Field of the Invention
The present invention relates to a photo film cassette. More particularly, the present invention relates to a photo film cassette of which a cassette shell is constituted of a plurality of plastic molded parts joined together by snap-in engagement.
2. Background Art
U.S. Pat. Nos. 4,834,306 and 4,832,275 disclose a leader-advancing photo film cassette, in which a leader of a photo filmstrip is entirely contained in a cassette shell, and when a spool is rotated, the leader is responsively advanced to the outside of the cassette shell. It has been proposed, as in U.S. Pat. No. 5,265,819 (corresponding to JPA 4-362939), to construct such a cassette shell by use of a pair of molded shell halves, which are joined together fixedly in a snap in fashion, such that a passage slot is formed for the photo filmstrip between the shell halves. On either side of the passage slot, a juncture of joining the shell halves is provided with a stepped structure, constituted of a groove formed in one shell half and a ridge formed on the other shell half for being force-fitted in the groove. This stepped structure is formed to extend in an orthogonal direction to the passage slot.